The invention concerns a device for contact-free supporting, turning and spreading of a web, in particular of a coated paper or board web, which device consists of a face curved in accordance with the turning of the web, in connection with which face the web runs supported by air blown in between said face and the web, the nozzle members in the device comprising guide faces and carrier faces placed in connection with the guide faces, gas, such as air, being blown through nozzle slots in the nozzle members, transverse to the direction of running of the web, onto the carrier faces, and which nozzle slots are, from one side, defined by the guide faces or placed in proximity to the faces.
With respect to the prior art related to the present invention, reference is made to the EP Patent Application 87102411.3, to the EP Patent Application 83303143.8, and to the U.S. Pat. No. 4,218,833.
With respect to some typical applications to use of the devices in accordance with the invention, reference is made to the Applicant's FI Patent 67,586 (equivalent of CA Patent No. 1,221,569).
With respect to the prior art most closely related to the present invention, reference is made to the device, described in the Applicant's FI Patent 64,335, in particular for contact-free supporting, spreading, and for possible turning of a coated paper or board web, which device's nozzle members consist of curved guide faces and of a pressure face placed between them, at both sides of which the pressure face nozzle slots are placed whose longitudinal direction is transverse to the direction of running of the web. In the FI Pat. 64,335 it is novel that the ratio of the width of the nozzle slots to the curve radius of the guide face is chosen in such a way that, with the occurring flow rates, the gas flow follows along with the curved guide face up to the pressure face and that the defining edges of the nozzle openings at the intermediate faces are sharp-angled to prevent turning of the gas flow onto the intermediate faces.